As a game designer myself, I've been considering what kind of civilization simulation might lend itself to a game like Space Engine, and thought I'd post my ideas here for discussion. This discussion assumes some basic level of animal simulation will be implemented at some point.

The likelihood of any given plant or animal species evolving to the civilization level (as we know it) is pretty low and depends on a very specific set of conditions to be met and remain stable for a significant length of time. There are places in this universe which are better suited to the evolution of civilizations than any other, and our galaxy is probably one of them. These places should also shift over time. As galaxies age, the environmental conditions within them change. Our galaxy is right about at the perfect age to generate lifeforms and thusly at the perfect age to nurture the development of civilizations among a very rare few of those lifeforms. This isn't to say that life and civilizations can't appear in galaxies that aren't at the same age or have the same conditions, but it's just much less likely, as far as we know.

Civilizations start out at the stone age, or an equivalent which represents only the most basic functions of the capability of a lifeform to recognize, pick up, and utilize objects natural to their environment which provide them with a new ability, such as clubbing a large creature for food, constructing a shelter, or constructing barricades or traps which effectively prevent certain lifeforms from moving out of an area (the precursor to animal husbandry). Arguably, a pre-civilization level could be implemented, which would have nomadic sentient creatures travelling across the planet following herds. However, these would behave much like animals to the outside observer and their sentience/intelligence would only become apparent after extended behavioral observation - this could be entirely abstracted, even so far as giving them an "IQ rating" which would come up as sensor data or somesuch, with no behavioral modifications or alterations to the appearance of the creatures necessary. Perhaps later stages of nomadic society simulation could put spears, clubs, or large rocks in the hands of such creatures, with no other indication of their intelligence necessary.

Most civilizations would not be capable of moving past the nomadic or early stone age level of civilization, because this is probably the slowest and most lengthy period of progress as we understand it, and there are a great many things which could happen during that length of time that could destroy the civilization. Civilizations face many challenges during their development and this is only compounded by the vast amount of time a civilization must survive with a level of technology that barely makes them any better than the other lifeforms they must compete with. Therefore, the vast majority of civilizations any galactic traveller would discover would be at this stage of development, provided they are even still alive.

For the most part we are assuming that the lifeforms capable of this type of civilization would be similar to humans - capable of using tools, non-aquatic (dependent on fire), dependent on water and air, and so on. Other types of life could very conceivably have some form of development or progress totally different from the civilization scale, thus we should not consider them part of this simulation mechanic. There could be differences in what kind of air a civilized lifeform can breathe, however. Perhaps Argon breathers or Hydrogen breathers are possible? Oxygen seems the most likely, however, and would promote the best chance of survival, mainly because it is also required for fire. They would naturally depend on food sources native to their home world. Drinking water is probably going to be necessary for any civilization, since water is necessary for the kind of life that would be covered under the civilization simulation. It's extremely unlikely (based on what we know) for a civilization to survive without fire, and this rules out underwater civilizations, but maybe not amphibious ones.

These assumptions make development of civilizations a bit simpler. It's true that a species may be able to develop space travel from an entirely underwater origin, but their development would have to be so different from what we understand as civilization that if we were to simulate it, we would have to use a different mechanic. For the purposes of this simulation, Civilization is defined as the social and cultural development of a human-like species. Human-like being defined as mobile, tool-using, water-drinking, fire-dependent, and air-breathing. This, however, does not narrow it down a great deal, and you could still have some very interesting possibilities, depending on how animal life is generated. A plant civilization is probably not possible with these assumptions, unless it can somehow move which is highly unlikely. However, sentient plants could have an alternative to civilization simulated through some other mechanic.

A nomadic species would be treated almost the same as any animal species on the planet. The simulation would need few special rules to represent them. These would be the most likely "civilization" to be encountered, assuming they are even represented.

A Stone-age tribal society would either dwell in caves or primitive huts. These huts would be procedurally generated mounds using textures derived from the planet's own texture generation engine, very similar to the ground texture, or possibly a plant or grass texture, or combinations of these. Tribal societies would arrange the huts in formations around a bonfire, most likely, or some other central construction, like a large "chieftain's hut" or meeting area. The formations would be procedurally generated, probably geometric but not necessarily. They could also be completely random, based on terrain features, or based on sky features such as binary suns, a nearby gas giant, star formations, or a nearby nebula or supernova remnant which is distinctive in the night sky. Artwork produced by the tribe could be based on these things as well. Additionally, stone age cultures could build monuments like stonehenge or cairns. These are simple arrangements of rock piles in geometric or other organized patterns. Again, star formations could be an influence here. Such formations could indicate primitive religions or cultural influences. Assuming a two-gender society, the males would leave the village regularly (night or day, depending on the species) to hunt and/or gather resources. The females would remain behind (with some males for defense) and tend to the village's needs, such as constructing new buildings, raising children, tending to livestock, harvesting and storing grain, etc. Males on the hunt would display the same behavioral characteristics as pack-hunter animals or nomads, with one difference being that instead of moving around the planet, they return to the village after the hunt. Alternatively, if they are like lions, then the females would do the hunting with the males tending the village. Hunters should have a mix of ranged weapons and melee weapons, so that they could kill some animals from range but would still have to rely on a melee weapon (such as a spear) to bring down the bigger ones. This requires them to hunt in large packs. This would be one thing that seperates the civilization hunters from animals. Herbivorous civilizations could instead just be foragers. Perhaps they would have larger farms in their villages. Additionally, fishers would just be hunters that move to a shore and throw spears into the water or stab into the water with primitive tridents to collect fish (it's too early in their development for fishing rods). Perhaps some could use fishing nets - but that seems a bit too advanced for the stone age.

This would be the extent to which the society's behaviors would need to be simulated. Ruins of civilizations would be more common than living civilizations, though few ruins from a civilization of this level would survive the test of time. It should be possible to rarely find the ruins of a stone-age society. Ruins would be generated just like the civilization but without any inhabitants, and based on the age, varying levels of structural decay. The huts would be eroded away or buried fairly quickly, with only stone tools being left behind to find - and those would eventually degrade as well, and probably only be found through some kind of excavation.

It is important to note at this point that the rise and fall of a civilization (as we understand it) takes place extremely quickly from an astronomical point of view, with each more advanced stage of civilization passing in a quicker timeframe. Where the universe is several billion years old, our own civilization is only several hundred thousand years old, if even that. Given this, the chance that we could just happen to discover another living civilization within the lifespan of our own seems astronomically small, and even smaller would be the chance that they would be on the same or a similar level of development as we are. However, you have to temper this with the sheer and vast size of the universe. There are just so many planets out there - literally beyond count, that these odds are basically impossible to predict. Perhaps the sheer number of planets guarantees that we will find other living civilizations. This largely depends on planets that support the evolution and long-term development of these civilizations.

Most civilizations will not survive past the stone age. Planetary environments change drastically over time and are influenced by celestial factors: meteors, solar activity, stellar phenomena (99% of which we do not yet understand). Our own civilization currently could be totally wiped out by a completely random confluence of celestial events, events which we have seen to be common throughout the universe. One could say that our survival thus far has been extremely lucky or divinely influenced. If the civilization is not wiped out by the environment, it could be wiped out by competing lifeforms, lack of resources, or itself through warfare (the latter two are often directly related - warfare tends to occur over a lack of resources).

The next stage of civilization would be bronze age (by human standards), or more generically, advanced tool use. This implies a culture which has learned how to manipulate the resources of their planet instead of just using the resources. Now they are capable of turning stones into masonry, and they can extract the metals from the rocks to create better tools. Hunting and resource gathering is less important and the civilization depends more on farms and crops. Their buildings are stronger, larger, and more advanced and take longer to decay in ruins. Procedurally generating a civilization like this would involve more organized formations of more advanced buildings, probably with a wall to surround each city. The building textures would be generated based on other planet textures but would not have to match them as closely. Arrangements of structures and monuments could still be based on sky features, but could also take a variety of other shapes, with more geometric and mathematical complexity. Or they could be random, or based on terrain features. The population of these cities should also be higher, and the people no longer look like animals, but rather they wear clothes now. In the stone-age it's probably not necessary to make the people look too different from animals because any clothes they would be wearing would be animal hides anyway. In the metal-age, sentients have access to dyes (of some form) and other luxuries, which makes them look very different from animals. They can also wear metals at this point. Gold should be common among most civilizations since as far as we know, a planet that supports civilization is created during a supernova, and gold is one of the byproducts of such a supernova, however if civilization-supporting planets can appear elsewhere, perhaps gold is not common to those civilizations. But this is speculation and likely not typical. Other precious metals are probably as likely. Although gold is considered to be rare to us, it's actually one of the more common elements in the universe. Though certainly not the rarest, and any civilization should use it as decoration, to mark valuable sites, objects, or individuals, unless there is so much of it on the planet that it's not as rare as it is on Earth. Gold isn't really useful for anything other than decoration at this stage of civilization, because it is too soft. Other metals, like iron, copper, and so on are also very common and thus would be likely for most civilizations to have access to. However, planets can vary greatly in composition, even planets that could support civilization, so there should be a great deal of variety among what other metals a civilization has access to. Perhaps instead of iron weapons, a civilization would have access to some element we've never seen before, and they make their metalworks out of that instead of iron - or perhaps an alloy of iron and this element.

Ruins of this type of culture would probably last longer but because this type of culture is less likely than stone-age, there would be far fewer of them. Though there are fewer, because the buildings take longer to decay, the chance to find actual buildings would be greater than with stone age ruins. The ruins should contain tools and objects constructed from common metals (like iron, copper, gold) but also any elements unique to the planet. Living cultures of this type would be much rarer than living stone-age cultures, but would be simulated in a similar way, with a few differences: * Cities have walls in most cases * Most buildings are more angular with fewer haphazard or rounded design elements: * Square or angled houses, paved or angled roofs, more geometric designs than the mound-like stone-age huts. * The buildings would probably stand out more from the local environment than stone-age buildings mainly because their textures would look less like the planet's natural terrain and be more varied. * Cities would have dirt streets or paved streets, with the paving texture most likely resembling cobblestone based on local rock textures. * A larger portion of the population will be seen walking around in the cities than outside the cities: * Farmers walk around in their farms, other people walk along the streets. During the sleep-phase (night, day, or some other time, depending on species), people "dissapear" into the buildings. * Outside the cities, smaller groups of hunters behave like pack animals. These hunting parties are smaller than they were in the stone age, even single hunters are possible, hunting like solitary animals. Unlike animals, however, these hunters have the ability to kill a beast at range, and this is the norm. * There could also be roads between cities, with traders and travellers occasionally seen walking between them * The civilization may have tamed animals to use as beasts of burden or mounts. These would be visible (in fewer numbers) wherever people would be seen. * Boats could be seen travelling between coastal cities.

The rest of it could probably be abstracted. Aside from observing a day/night (or similar) cycle, the activity of the people would not have to be too complex. Text information could fill in the blanks, as it is easier to generate than displaying the individual motivations and behaviors of each individual member of a civilization. If further abstraction is desired, preventing the player from getting too close to a civilized planet could be an option (perhaps a prime directive). This way you could only observe a civilization from orbit or from an uninhabited part of the planet, thus limiting the amount of graphical detail needed to be displayed.

Higher levels of civilization become progressively less likely as the chance for a civilization to die out increases. Each level should increase the amount of complexity of the civilization, but would also necessitate a higher level of abstraction in the engine in order to prevent the engine from slowing down too much while simulating it. A cheap and easy excuse to do this would be the above mentioned "Prime Directive" which prevents players from getting too close. Scaling this by the civilization's level of development is logical and makes sense - the early civilizations would be less effected by close observation, whereas the more advanced civilizations would have better detection abilities and would be more heavily influenced by what they see as alien observation. However, part of the fun of the game could be to influence civilizations and see how they turn out. That's a gameplay decision that would have to be made.

Higher levels of civilization also spend less time advancing to the next stage, therefore Industrial and Modern age civilizations should be almost impossible to find, with Nomadic and Stone age civilizations being the most likely. Ruins for these civilization stages would be more common than the living versions, but still follow the same scale with Stone age ruins being more likely. However, the ruins of a Stone age culture would most likely be limited to a few tools buried in the dirt here and there (probably not even something you could see if you were standing there), with huts only being present shortly after the demise of the civilization, say within 100-200 years. By contrast, the structures of a modern age society with its towering skyscrapers, vast global infrastructure, and usage of non-biodegradable resources, would last for a much longer period of time (thousands of years potentially), though quickly become overgrown by the planet's natural environment once abandoned. This would create vast ruinscapes and a wealth of archaeological data to collect and study.

Alien intergalactic civilizations would not be influenced by outside encounters in the same way as a pre-intergalactic civilization would be. To them, the player would simply be a foreigner, not necessarily a more advanced species that challenges their primitive understanding of the universe. However, simulating this gets into a much larger gameplay dynamic that seems to fall outside of the above civilization dynamic, where things like war, diplomacy, trading, and politics between the player and the aliens would have to be represented. Not to mention that realistically, such civilizations would be few and far between, requiring a very specific mix of ideal and long-term stable conditions for a species to advance to that level.

Shadowstar, you are describing the evolution of our civilization. You are too anthropocentric. Alien civilization and even alien life forms unimaginably differ from our own. You say aquatic civilizations are impossible due to impossibility of using fire. But I would disagree with you - there are many ways of making tools without using fire. Europa-like planets may develop a civilizations that uses underwater volcanoes as an energy and chemical substance source. They can never reach space and live during millions of years in a stable state. Or they may make huge lenses using water ice and focus solar light to obtain high temperatures to perform chemical processes. Such lenses can be observed from space as anomalies on the planetary surface. There is a possibility of developing life forms on the planets witch have no oxygen, nor any other chemically active gas in their atmospheres - and fire will not be possible on that planet. Civilization may build lightning-conductors and use energy of lightning to melt stones and extract metals or use solar energy. Civilizations on a tidally-locked planets near red dwarfs may use the energy of powerful permanent winds in their atmospheres, and effectively use solar energy because the sun is not moving in their sky. Development of many civilization may have no human-like stages - this is depend on biosphere structure and usable energy and material sources. A civilization of flyers do not need roads or even concentration of their entities in a cities. Underground civilization may have no cities but a huge network of tunnels penetrating the planet, and so they may not be observable from space or even from the surface. They may use unlimited geothermal energy and inexhaustible supply of minerals, tens of kilometers deep inside the planetary crust, so they may have stable development for thousands of years without wars and the necessity of cosmic expansion. Some human-like civilizations may build underground structures too, if they found them more effective than buildings as we have them. Many civilizations may end up their developing in a virtual reality, or turning themselves into cyborgs and then into machines. Such civilizations may look like a network of powerful (and compact) computers, placed in well protected chambers with a solar or geothermal energy source, with some repair robots. More advanced civilizations may live in space stations or in full self-sufficient spaceships, flying through the galaxy and avoiding all contact. We may never realize this: that we maybe surrounded by an advanced civilizations, becuase they don't live on a planet and don't use conventional communications and engines for their ships.

But the main problem is that procedural civilizations are impossibe. Procedural means that the object does not exist in memory until you reach its observation point, then it gets generated using a pseudorandom number generator initialized with a seed that is computed from the parent object's parameters (planet, star, galaxy). No other information can be used. In this way it is possible to generate planets, cities, ancient ruins - static features. But a living civilization is not static. It is possible to generate procedurally, billions of moving humans and vehicles, but their movements should be analytically defined. I.e. there should be a function that calculates the position and orientation of the object, based only on time and the parent object's parameters (city, planet). You cannot interact with the procedural object. I.e. you may land in the shuttle on the main city square and humans will still ignore your ship. Some fake reaction simulations can be implemented (humans may scatter in panic), but there will be no effects from your actions in the future. Because procedural generation is a static feature.

We need a full simulation, which is impossible for modern PC. The entire civilization should be modeled to save the effects of your interaction with it. This means that any human, vehicle or building should be computed with AI, and at every time, even if you are far away or not in the game. Some optimization are possible - computing affected units only, interation with abstract "civilization goverement" only, etc. Full simulation is only possible at a "toy scale", like in Spore, where all civilization is 10 cities with 10 buildings and 100 humans each.

I agree that many different types of civilizations are possible, including underwater ones and those who do not use fire, but each specific type would require an entirely different simulation model, though each model could be based on something more fundamental. What I was describing was just one model, using our own civilization as a template. I find that in game design, it's best to start with what's most familiar to you, and the simplest implementation of that (nomadic/stone age), and then build up from there. Once you have the framework in place, you can begin to expand the system into other areas. For instance, once you have working stone-age ruins in the game, you can essentially copy that system, alter it to simulate an equivalent underwater-based society, or gas-giant based society and so on. However, personally I don't think you could really consider these "civilizations", because they would be so different. Would a hive-mind be considered a civilization? I suppose it's debatable. It seems some other word would be more fitting though, maybe something more general like "society" or "community". It's something to think about. Then again, calling them all civilizations does keep them simple. It's just that, in my mind, "civilization" refers to the development of the society of a human-like species.

In any case, regardless of what we call them, they represent the ability for any lifeform to evolve to a point where it becomes sentient and capable of manipulating its environment to support the rapid advancement of its species. This is a rare process and because of the conditions necessary for it to occur, it seems there should be a relatively small number of possible types. The one type I described seems like a good starting point, because it's something we are all familiar with (our own society). Whether to simulate living societies or not really depends on how much time you want to put into it, and how much we can realistically simulate with current technology. I understand the limitations, which is why I suggested the "prime directive" as a way to keep the player from getting close enough to the planet that the simulation would become overly complex. But, to be honest, I don't really like that idea a whole lot because it limits the player and SE seems to be against limiting the player (which is good in my opinion). Therefore, the logical compromise is just not to model living civilizations at all. But we should still be able to find ruins, in my opinion. So perhaps, for the sake of practicality, that should be our starting point - the ruins of a stone-age human-like civilization. From there, metal-age, renaissance age, industrial, and so on could be developed, and then alternatives like ocean-based, gas-giant, lunar, and maybe even space-bound society ruins could be considered. However many you feel like creating, of course. Each type could be a fascinating exploration of what might be possible, and to the player, the discovery of such ruins would be a rare and monumental thing. Enough that it could be the sole reason some people play.

But the main problem is that procedural civilizations are impossibe. Procedural means that the object does not exist in memory until you reach its observation point, then it gets generated using a pseudorandom number generator initialized with a seed that is computed from the parent object's parameters (planet, star, galaxy). No other information can be used. In this way it is possible to generate planets, cities, ancient ruins - static features. But a living civilization is not static. It is possible to generate procedurally, billions of moving humans and vehicles, but their movements should be analytically defined. I.e. there should be a function that calculates the position and orientation of the object, based only on time and the parent object's parameters (city, planet). You cannot interact with the procedural object. I.e. you may land in the shuttle on the main city square and humans will still ignore your ship. Some fake reaction simulations can be implemented (humans may scatter in panic), but there will be no effects from your actions in the future. Because procedural generation is a static feature.

Well, I thought about this 'staticness' of procedurally generated objects (textures/models). Only solution is to be able to dump whole planet which houses civilization on the fly, then release such planet from being procedurally generated removing player inability to interact with them. Though this would work only in single player, since server would need to have exabytes of storage for every player

Other way around is to ignore single individuals altogether. You don't see people from space, heck, you can't easily watch single people from 1 kilometer without binoculars.

My vision is probably impossible, since there is plenty of CPU/GPU/RAM limitations. Here it is: When you generate a planet, engine should link area types (i.e.: plains, valleys, mountains, oceans, lakes, rivers, forests, swamps, volcanoes, craters, just to name a few) to allow them to interact with each other (and player of course), and to be modified outside of procedural engine. This way you can analyze planets amount of water, forests, deserts, etc., also player gains ability to really interact with procedurally generated content since he is not messing with it directly, but with it's link. You don't save gigabytes of data, but simply you save changes made to such planet (which couldn't be many), for example something like "y_pos,x_pos,plain,link_y,link_x,link_z,impact=100kN to link_y,link_x,link_z" which is 100 kilo newton impact on some plain on the planet, from where it starts, and where it ends. We don't need to save details, because again procedural generation kicks in, and another player that visits this plain on this planet will see effects of dropping few km asteroid from the orbit done by some rascal

So, again, for first time visit on a planet: 1st) we generate a planet with all it's attributes; 2nd) linked areas are rendered instead of procedurally generated content; 3rd) we modify a planet to some extent (drop a bomb, build a city, build a mine, etc). 4th) everything is send to server in some intervals (or hdd if it is single player) 5th) server checks if there is a player in vicinity, then sends him/her changes done by other players (or by for example random events);

Planet that had some changes: 1st) server sends list of planets/objects that were changed lately; 2nd) we generate a planet with all it's basic attributes; 3rd) linked areas are rendered considering everything that was changed;

Problem is, objects are hollow inside, any damage would need to consider depth and durability of both objects that collided. It is possible to crush two planets, and such simulation on the fly is kind of hard to imagine. Hopefully, there won't be possibility to do such thing. Also, tsunamis are probably not possible this way.

Going back to civilization generation.

If we have such linked areas then we can generate objects that fit area they are in. For example trees in a forest, or ruins of some huge building (an altar for some god perhaps? or ancient rocket launching pad? or both?) inside a forest. There is lots of possibilities here.

Link areas could contain some other resources, like iron or materials like mentioned further clay or even uranium. While it is problematic to mine on a planet and transport it to trade with someone, asteroids are easier source of materials, link areas could also be used with these. Though linked, it wouldn't need to change visually (planets nor asteroids), since only big mines would be able to modify terrain enough to be noticeable. Just an arbitrary number indicating amount of resources in an area would be sufficient.

If there are trees on the planet, then it is most likely that any humanoid civilization will use it as their first resource. Aquatic species could gather clay and form objects using underwater volcanoes, or use underwater vegetation to create clothes, etc. Aves species could build nests (trees again?) in high, mountainous area. I could continue, though I suppose everyone here could expand on this topic

After we generate type of species, their technological levels (in some areas we are geniuses, in some we lack heavily), we can generate their cities or buildings, considering of course linked areas. Aquatic species live in or near water, aves are only seen in mountains, etc. Since we would never see them in 3D (maybe a procedurally generated image when communicating with them?), only distinction between civilization would be their architecture. While humans tend to live in tightly packed cities, some other creatures may prefer nomadic lifestyle, or they could live few centuries in loneliness just to meet in one place to make offspring. Keep in mind that some creatures don't need roads to travel even under load.

Species gather where is food and easy access to water or other necessities. First cities started in such areas on Earth, so we can assume that most living creatures are going to behave in same way, unless they live nomadic lives, or they are loners, etc. After analyzing these basic traits (average size, habitat they live in, lifestyle, physiology, etc), engine can generate simple housing (pre made? fully procedural? mixed?), or even vast cities, according to linked areas and their properties.

If they see in the dark, are completely blind, or detect and emit radio waves with their bodies, you won't see them on the night side of the planet. If there is few of them, or they live in seclusion, you also won't detect them. Underwater species are also hard to notice, and those living underground are absolutely out of reach. If you would land on Earth ten thousand years ago you probably wouldn't even notice humans, or their cities. There was around 5 million people then!

So, generating civilizations that are small and spread across their planets is not so overwhelming task. It would be overwhelming for a player, or even whole group, to find them

Creating huge and complex civilization is no small feat though. They could live in huge stone castles, wear iron armor, wield gauss rifles and have a colony on one of their planets moon. Other such civilization could be living absolutely oblivious to space, because their world would have level of never ending fog covering whole planet. There are myriads of combinations, everything depends on habitat, type of sun planet orbits around, species life length, behavior, ability to set longtime goals, work in group, pass knowledge, etc, etc. I guess without simplifying some aspects it is really impossible, with our current technology, to procedurally generate whole, really advanced, civilizations. It's certainly easier to create flotilla of giant ships which would house some sentient race instead of trying to place them on surface of a planet.

Still, in vast space, life would be something really, really rare. Chances are, that player, through his or hers whole game play, will never encounter sentient alien life, only ancient ruins or a space probes sent from far, far away, both in space and time.

I Agree with the simulation and exploration of Civs. and also would be awesome to interact with the member of the civilization, but it would require lots of 3d models. Or it could be like spore, with a more "random" model aproach... In spore all creatures could be randomly created if u press "randomize" when creating a creature. but in other hand if we were to generate humans, and human-based civilizations , we only require human models, even if they are ridiculous and basic, low poly and low res textures, every human would live in an entity called city or tribe or something , with preset models for buildings! I also would like to see flora and fauna!

After completing the geological phase/ocean formation you get single-celled life, then multi-cellular microorganisms, then all the various taxa. Any taxa can achieve civilization status if it evolves high enough intelligence. The civilization then proceeds through various technological eras (stone, bronze, iron, industrial, nuclear, information, nano) and finally become totally space-faring and leave the planet behind as a nature preserve.

You can control various aspects of the environment (solar input, rainfall, greenhouse effect, volcanism) as well as biological factors like the mutation rate. You can also control various aspects of civilization (energy production from various sources and investment in agriculture, science, art, philosophy etc). Fossil and nuclear fuels are limited and overuse leads to global warfare. Overpopulation can cause environmental catastrophes and mass extinctions, burning fossil fuels adds CO2 to the atmosphere, and nuclear warfare makes land uninhabitable.

You can play in sandbox mode or with a limited energy budget for changing sliders. Energy is steadily replenished over time if you aren't playing in sandbox mode. It also includes special Mars/Venus terraforming scenarios and the necessary tools. You also have disaster tools (earthquakes, volcanoes, storms, ice/rock asteroids, nukes...).

I'd love to fly around the universe discovering life/civilizations in various states of development with the option to park in orbit and take control in a similar fashion.

Even if simulated life isn't possible I would LOVE to see giant procedural cities, ruins, structures, other static features. That would be amazingly fun, exploring detailed ghost towns as long as the building types would be extremely varied and almost completely different from every other planet with them.

So you're basically suggesting that a Civilization style element be incorporated? It would most likely be extremely difficult and would take a very long time to implement. I would not expect it in the near future, or ever. It would be pretty cool, however.

I am the game master of a civilizational forum game (http://amauvala.forumotion.com) where every player is developing an own human civilization (the game is set on an alternative earth-like world). There are tons of NPC tribes. For the game, I have tested a thermodynamic economic model where a civilization can only arise if early neolithic peoples manage to "break the equilibrium" (produce a food surplus).

There is also a spreadsheet with sixteen symbols that players choose from. This can lend itself to 4096 individual directions for civilizations.

The problem in such a game as Space Engine however is that hypothetic civilizations would not necessarily be humanoid. We can easily imagine cephaloid, reptiloid, ichtyoid or insectoid sapient life emerging, and that would give a lot of different combinations. Moreover, brain structure would lead to different social outcomes in inter-species behaviour. That is why most alien races in the sci-fi genre are either extremely simplified or represent non-western stereotypes, because we don't possess the capability to simulate non-human neurological wiring which would produce true, 3-dimensional social behavioural patterns.

Sorry for using an excessively long sentence there.

Here's a representation of a typical tribal constellation. It is quite simple as it is still in the palaeolithic age, and there is basically only one resource (food) to keep track of. When we enter the digital age, there might be hundreds of resources, and yet they would not accurately represent the full diversity of the ecological structure of a civilization.

Added (27.04.2013, 04:50)---------------------------------------------As for development, it is a gradual process stimulated by numerous self-reinforcing factors. I represent this process in "Civ Points", which represent experience and the amount of inter and exter communication of a society that is increasing the rate of creativity. There is also an exponential factor which makes increasing amounts of Civ Points reinforce themselves slowly over generations.

Instead of technologies, I have chosen to have technology levels such as engineering and so on, which unlocks both new inventions and a generally higher rate of production.

I would love a Civilisation system implemented, however as stated, it's not possible to have a procedurally generated Civilisation.

The easiest and simplest way to have one is for it to be text based. That bypasses all the issues, and gives us an ability to have an "imagined" civilisation rather than none at all.

Personally, I'd rather it be text based to not having it at all.

one solution to showing advanced civs and cities on a planet is to prevent the player from ever landing on planet. The city lights could still be visualized on the planets texture map for a bit of immersion.

If the civ is advanced enough, you could just say that they have air space defense systems that prevent alien ships from landing. If you get too close to the planet your ship will get destroyed. At best, there could be a text/image based communications with civ from space. Maybe even a space station that you can opt to land on instead.

this may be slightly better than landing on a barren planet with only text knowledge of their being an advanced civ.

Would be a problem to show all civilisations as hostile who actually shoot every ship approaching.

Having a full simulation could indeed be a problem. If a planet has a civilisation, then the only way would be to generate certain objects procedurally and the other after some guidelines. Simulating the whole civilisation wouldn't be possible aswell. So it would be more a number calculation and until you get there and down, the game would start the real calculation. Similar to the ideas for flora and fauna.